Memories, memories....
I was young when the High Fidelity was in its golden age. During this period, a lot of firms were in competition to satisfy the clients by delivering the best possible products. The financial directors and the marketing were paid for their job, not to design the products ! The engineering was key to get good reviews and good feedback from the customers.To become a high end firm, and to belong to the cream of the audio manufacturers, the look and the marketing were not enough and were not the key: it was absolutely mandatory to issue a few products that were really out of the current standards by providing a really exceptional musical performance.

A firm located in New Zealand named PERREAUX did understand that fact, and issued in 1985-1990 a range of excellent products that made its reputation for a few years, and pointed the brand "Perreaux" out of the vast majority of common audio brands. These products were 2 amplifiers, the PMF-2350 (2 x 200W) and the PMF-3150 (2 x 300W), with a stunning transistor based preamplifier, the SM3.

Just to remind us the pleasure that we had to discover these famous Perreaux at this time, here are a few photographies of the PMF-2350:

which was a bit more musical than its big brother, the PMF-3150:

But in parallel to these two amps, a preamplifier appeared to be one of the best preamp it its price range and has created a surprise and got enthusiast reviews and feedback, the SM3 that we are looking in detail.

This beautiful baby has ... 28 years old (!) like this official Perreaux cover shows:

It is up to you to believe (or not) if the current audio devices will still be of any interest in 28 years from now...

This SM3 has clearly contributed to establish the Perreaux brand in France and probably in Europe and overseas. My lack of interest in Perreaux started when the Perreaux devices began to join the vast majority of the other audio products, I mean paying more attention to the look and marketing than to the musicality and quality. I may be wrong, but it seems to me that Perreaux has lost its reputation after this serie of products, and did not remain in the cream of audio manfacturers. But have a look to the current MARANTZ or INFINITY products and you will see that it is probably worse, and we do not list the brands that have simply disappeared !... The HiFi golden age was over...

But let us go back to the SM3 and its particularities:

the preamp is very thin, so it has a nice look event if it was not the only one to have this form factor

the internal parts are rigorously implemented. It looks serious. The top plate has small holes on its entire surface

the power supply is large for a preamplifier: 12 x 4,700µF = 56,400µF, whereas the transformer might be larger. A lot of power amplifiers do not have as much, (be sad for them...)

this transistor preamp operates at high voltages (>80V); it is the only one that we know, that operates with such high voltages.

the phono stage is excellent, support MM and MC, and can accept an additional load throuh dedicated RCA connectors

and finally a delicious blue bulb that lights when the device is on: this made every Perreaux easily identified at this period, because the blue was very rare.

This used SM3 that I have upgraded belongs to a friend of mine, but I am the initial owner: I bought it in 1987... When I got it back, there was so much dust inside that I ask myself: should I keep it or should I throw it ? Of course, it is strictly prohibited to throw a SM3 !

II-.THE UPGRADE.

The first action was to remove the dust from the cabinet : a 5mm carpet of dust had taken place inside the cabinet !...The vaccum cleaner was necessary to see the printed circuit board ! Then, plug it into the AC and check if it is still operational 28 years later ?
YES ! a true pleasure ...

Over this first step, and we immediately came to the conclusion that this preamp has a lot of electrolytic capacitors, that must of course be replaced after nearly 3 decades... There are 12 electrolytic capacitors for the Power Supply and apprximately 30 for the rest.

II-1.The Power Supply.

The SM3 Power Supply uses 12 capacitors marked "Perreaux", each one being a 4,700µF 50V 85°C. It would be nice to increase this capacitance, but you have to quickly forget this idea because there is not enough space (particularly not enough high) to place bigger capacitors. Each one is 35mm diameter and 30mm height.
So we have replaced them by 12 Panasonic capacitors, labelled 105°C. The total power supply remains therefore unchanged at 56,400µF, which is huge for a preamplifier.

The transformer must also deal with the small height of the SM3. It is labelled TX-TD83 but there is no information related to its power, the Service Manual says nothing more about its power and Perreaux has no more information (I asked them). It has 2 secondaries that deliver a high voltage for a transistor preamp, 76Vac and 38Vac, delivering 90Vcc and 45Vcc to the SM3 stages ! This Perreaux SM3 is one of the very few transistor preamp operating with such high voltages...

The rectifier diodes belong to the following families:

the common and crappy 1N-4004 (very suitable for a coffee machine, but not high end audio at all...)

the 1N-4848 supposed to be high speed diodes.

By looking carefully to the printed circuit board, you see that the 1N-4848 diodes are located in places where the space around is very limited : therefore it would be extremely difficult and risky to replace them, so we have decided to replace only the 1N-4004. These are mainly used for the rectifier bridges just after the transformer. As always, I have our reference high speed diodes, the same that we have used for our two Threshold Fet-10He upgrades.

The other chemical capacitors (not belonging to the P.S.) are labelled "MARCON 105°C". They have all been replaced by the NICHICON MUSE KZ, same value same voltage.

II-2.The rest of the circuitry.

As we said before, there are approximately 30 other electrolytic capacitors in the preamplifier, and for them too, after 28 years of service it is (more than) time for them to retire.
So, they have all been replaced by their NICHICON MUSE KZ equivalent, except 2 of them that have been replaced by two NICHICON Fine Gold because the exact value does not exist in the KZ serie.
Here too, the very limited height of the SM3 obliged us to sometimes place the NICHICON caps horizontaly. It is not difficult, you just have to be careful. Of course the final look is impressive:

You can easily see on this photo the crappy RCA connectors in the back, that were still present at this step of the upgrade.

A 28 years old SM3 totally recaped with the NICHICON MUSE KZ, I assure you that it looks beautiful !

II-.The internal cabling.

Another point that got my attention was a few small cables that are located in the back of the SM3, and run on the surface of the printed board. These cables are obviously far from the best available today, but please remember : 28 years ago, nobody paid attention to the cables !
By looking closely to them, I even saw that a sleeve was lightly damaged, with no risk at all for the circuits, but the time had made its job...

In addition, the MM/MC Phono switch appeared to be very difficult to move, like if the oxydation had won the battle against the internal contacts. It was still operational, but I decided to change it, as it is simple to do.

Look at this photo to understand and follow the route of the small cables that I have just talked about:

Amongst these small cables, 2 of them go through the printed board using two holes, and then continue on the other side to reach a ground point near the RCA connectors:

So I have changes the MM/MC Phono switch, all these cables have been unsoldered and replaced by pure Copper UP-OCC Teflon insulated cables (this changed has required to temporarily remove a WIMA capacitor, that has been of course soldered back after the cables replacement).

II-4.The upgrade of the RCA connectors.

If you at the following phot, you can see that all the cables have been changed, but also that the crappy plastic RCA conecctors have also been replaced by excellent pure copper, Teflon insulated ones. These new RCA connectors are linked to the printed circuit board by UP-OCC Teflon insulated cables. They are a good choice because they are screwed from outside the preamp and consequently you can solder them before firmly screw them.
As any high quality connectors they are expensive (approx $200 for the 9 pairs).

It is impressive, but if you look at the rear face, it is maybe even more significant:

II-5.The potentiometers upgrade.

The SM3 is equiped with an ALPS blue potentiometer (2x50k), that has an excellent reputation as a potentiometer. But I wanted to mount a GOLDPOINT attenuator, the same that I have installed my upgraded Fet-10He. unfortunately, 3mm are missing in height, but it seems possible to mill the frontplate: I wil keep you informed about this.

As I am temporarily obliged to keep the ALPS, I have decided to remove the Balance from the signal path (it is totally useless: who uses the Balance ?) and to replace the stock cable by our high quality UP-OCC Teflon insulated cable between the ALPS and the printed board. The original cabling between the ALPS potentiometer and the printed circuit board is probably the worst part (with the crappy RCA connectors) of this preamp: it is a sort of thin and low cost computer cable (see part #3 in the center of the photo of the replaced parts below).

Here are the parts description:

1► the On/off cable that was linked to the On/Off switch
2► the cable that was linked to the Monitoring switch
3► the worst of all, the cable that linked the ALPS potentiometer to the printed circuit board. A true horror...
4► one of the cables that run on the surface of the printed circuit board
5► one of the cable that was linked to the Phono MM/MC switch

And herebelow you fill find a photo of most of the parts that have been replaced:

I Cannot finish this tour without talking about the famous blue indicator that was a distinctive sign of the Perreaux brand in the late of the 80'. At this time, most of the indicators were green or red; when a blue one was there you were quite sure that it was a Perreaux ! On this device the indicator was out of order: no light at all. So I had a look at the problem and I have been very surprised to see that it was not a LED but a bulb ! I suppose that the blue LEDs were very rare at this time... Of course I have replaced it by a blue LED with a resistor inserted in serie.

Here is my Perreaux SM3 : better than it was when it was new !

This article will of course updated with the listening sessions, and probably with another set of parts replaced. Stay connected !